record module simplified with a saner file name template, and the date is set once at program startup instead of changing with every save

new tiling module to handle all tiling state

new zoom module to handle all zooming state

render.h defines a struct render_options for all control over rendering, it has a flag set if paramters have been changed that require rendering to restart, otherwise the new visualisation parameters are applied live

Other internal changes:

fp___escaped "flush" flag removed, now the necessary functionality is in fp32_colour "done" flag and fpxx_init without rasterizer discard